1. Calculators everyday this week!
Agenda 4/6/10
Collect Bouncing Ball Lab.
Acceleration and Deceleration (page #10).
Start homework.
Homework:
Acceleration Calculations WS (page #11).
Motion Quiz on Friday (see motion study guide and topics sheet)
Calculators everyday this week!

2. Acceleration and Deceleration
ACCELERATION measures the change in the velocity of an object.
For example, a car may be accelerating at 5 km/hr for every second.
This means that every second the car is going 5 km/hr faster.
Therefore, the first second the car is traveling 5 km/hr;
The second, second________________________.
The third second __________________________.
To solve for acceleration or deceleration, you must know the objects initial velocity (Vi) and final velocity (Vf) of the moving object and the time between these two velocities.
10 km/hr
15 km/hr

3. New Formula Acceleration/Deceleration (a): a = Vf - Vi t
Vf = Final Velocity
Vi = Initial (starting) Velocity
t = time

4. Sample Problem #1 If a stopped car obtains a velocity of
60 km/hr in 10
seconds, what is its
acceleration?
a = Vf - Vi t
a = 60 km/hr km/hr
10 seconds
a = 60 km/hr
10 sec
a = 6.0 km/hr
sec

5. Sample Problem #2 What is the acceleration of a grasshopper that
jumps from standing
still to a final velocity
of 50 m/s in a time of
0.25 seconds?
a = Vf - Vi t
a = 50 m/s m/s
0.25 seconds
a = 50 m/s
0.25 sec
a = m/s or m/s2
sec

6. Sample Problem #3 What is the acceleration of Lindsey who ran the
100 m dash if she
reached a speed of 19
m/s in 9.5 seconds?
a = Vf - Vi t
a = 19 m/s m/s
9.5 seconds
a = 19 m/s
9.5 sec
a = 2.0 m/s or m/s2
sec

7. What is deceleration?
DECELERATION is simply negative acceleration. It measures the change in velocity of a moving object that is slowing down. When brakes are applied to a car, it is decelerating.

8. Graphing Motion
All motion continues in a straight line unless an outside force is exerted upon it. All motion can be expressed as a graphing relationship between distance and time. A graph for constant speed is always a straight line such as the one at the right measuring the speed of two cars.
Which car is moving faster? Explain.
Car A
Car A has traveled a greater distance in a shorter period of time.

9. Graphing Motion
Examine the graph. Explain what happened at section B of the graph.
Car had stopped!

10. Graphing Motion
Use the data table and graph grid to the right. Graph the speed of the car that traveled 500 km in 5 hours. Make sure to correctly label the x-axis and y-axis.
Data Table
Time (hrs)
Distance (km) 1
100 2
200 3 4
400 5
500
What was the car doing between the second and third hour?
Stopped.
Did the car go a constant speed during the journey?
No. Car stopped for a portion of time.

11. Graphing Motion
What is the shape of the line on the graph for acceleration?
What is the shape of the line on the graph for deceleration?
DOWNWARD
UPWARD

12. Graphing Motion
Using the deceleration graph, what happens to the distance traveled per unit of time?
Distance decreases as time increases. Object is slowing down (decelerating).

13. Speed vs. Time Graphs ACCELERATION
Remember we know have two (2) acceleration graphs:

14. Speed vs. Time Graph DECELERATION
Remember we know have two (2) deceleration graphs:

15. Speed vs. Graph CONSTANT SPEED
Remember we know have two (2) constant speed graphs: